What's wrong with my car? I keep needing to jump it all the time.....?

I drive an 86' Honda Prelude. I recently replaced the alternator, external regulator, and battery in my car. The car ran fine for 2 days then on the 3rd day when I went to drive my car wouldn't start. I got a jump and it ran fine. I even let it idle for 20 mins. to charge the battery. Early this morning when I headed out to work, the car wouldn't turn over. I needed another jump. I had to jump my car to make it home also. If I get a charge, drive, then shut it off, then turn the key right after, the car will start. If I leave my car off for more than a few hours then my car won't start. What is going on with my car? I need answers I'm tired of jumping my car.